PRODUCTIVITY OF NEEDLES AND ALLOCATION OF GROWTH IN YOUNG SCOTS PINE TREES OF DIFFERENT COMPETITIVE STATUS

It has been suggested that the allocation of carbon to stem wood growth has low priority, and that productivity of needles (above-ground tree biomass increment per unit leaf weight) decreases as competition between trees increases. To test this, carbon allocation to different growth components and productivity of needles were compared between trees of different tree classes (dominant, codominant, intermediate and suppressed). The study was carried out in two 16-year-old Scots pine (Pinus sylvestris L.) stands, planted at different initial densities: 40 000 and 10 000 seedlings ha-1. It was found that the allocation of carbon to stem wood production, and probably also fine root production, has high priority for trees under high competitive stress. It was also found that production per unit weight of needles increases with competition; at least for as long as the trees are experiencing approximately the same light regime.